A conventional single cylinder type switching valve of this type is composed in a cylindrical shape to open or close inlets for hot and cold waters and to adjust the mixture amount of the hot and cold waters in the same valve body, and operates to open or close the inlets for the hot and cold waters by axially moving the cylindrical valve body and to reversibly adjust the openings of the inlets for the hot and cold waters by turning the valve body to adjust the mixture amount of the hot and cold waters.
The cylindrical valve body of the conventional switching valve is sealed only by sealing means of O-rings made of rubber or synthetic resin provided at the cylinder side. The O-rings are vigorously worn or damaged by foreign materials such as sand, gravel, rust pieces of pipes mixed in the hot and cold waters to be supplied, and thus has disadvantages that the O-rings early leak the waters.
Calcium, iron, cake and/or a sterilizer such as a chlorine contained in the water to be supplied are adhered to the O-rings to early deteriorate the O-rings, to increase the sliding resistance of the O-rings with the valve body, and the switching valve thus has disadvantages that much greater strength than that at the initial time is required to operate the switching valve.
Even if the sliding surface of the valve body of the switching valve is coated with a lubricant to reduce the sliding resistance of the O-rings with the valve body, the cylindrical valve body is axially moved to open or close the inlets for the hot and cold waters and is rotatably adjusted in the openings of the inlets for the hot and cold waters. Thus, the sliding surface of the valve body contacted with the hot and cold waters is extended in a wide range, and the lubricant coated on the sliding surface is immediately flushed away so that it is very difficult to maintain the initial sliding state on the sliding surface.
A conventional switching valve, wherein a cylindrical valve body and a cylinder are formed of a stainless steel or a ceramic material having less chemical change, less wear and high hardness to enhance the strengths of the valve body and the cylinder has been proposed, but it is difficult to precisely finish the cylindrical shape with the high hardness material. Even if the cylindrical valve body and the cylinder are formed of the high hardness materials, the sealing with the O-rings is still indispensable.